McLean, who leads Nielsen's own children's reading conference coming up next on 16 September in New York, arrived with a huge battery of survey data from Nielsen's Bookscan, Books and Consumers and Children's Deep Dive research work, and also from third-party material comprising survey data from Pew Research and the Book Industry Study Group (BISG).

We have a tendency in the publishing industry to only think about our customers when they are reading. In our minds, they are always reading. And the truth is that they are not always reading. It's important now that media have become so distributed and so porous to think about what else is going on in these households. And that's how I've tried to focus my research at Nielsen, to think about to look at the full 360-degree view. It's not enough for us to focus on what's going on within the four walls of the publishing industry.

In a glimpse ahead at some of the kind of material Digital Book 2015 attendees will hear today, Thursday, in a session with author Peg Tyre and Scholastic's Francie Alexander on differences in boys' and girls' reading ("Readers Left Behind," Javits Center Room 1E09, 9:50-10:35 a.m. ET), McLean indicated that reading for pleasure for girls starts earlier than boys do, and the decline of that activity ends later for girls than boys, too:

This is a parent-reported statistic in pleasure reading. It starts to peak for girls at age 5 to 6. It doesn't start to peak for boys until 7 to 8. This has been a very consistent figure for us since 2010. More than 50 percent of girls aged 5 to 10 are reading five to seven days per week. But we also asked the same question of teens about how much do they read for fun. And teens generally, in self-reporting since Fall 2011, has shown reading for pleasure dropping pretty precipitously. We were kind of in a panic around Fall of 2013. Generally, we're seeing some bounce-back.

Where teen reading for fun had dropped to a reported 59 percent in that Fall 2013 period McLean mentioned, Fall 2014 saw some 66 percent.

'Tablets, tablets, tablets, tablets.'

Of special interest to us here at The FutureBook, McLean took up the question of digital reading among teens in her IDPF report.

Are kids reading? Yes, they're absolutely reading. How are they reading? Mostly in print.

When it comes to devices, McLean said, 'The story of the children's book market is tablets. Tablets, tablets, tablets, tablets." Tablet penetration in the book-buying households of the US, McLean reported, "has now reached 58 percent, more than double the penetration of standalone e-readers." The surveyed percentage for e-reader penetration, she said, is 26 percent.

It’s hard to overstate the impact tablets are having on the children’s market, and these devices are not only driving digital growth in the book market, they are impacting all areas of children’s content.

One of the most widely debated issues in US children's digital-reading discussions has been the viewpoints of parents about e-reading and print for their children. What McLean described was a persistent divergence of opinion among parents: many can cite the practical reasons for what appears to be a wide exposure to tablets for kids at a very young age — and yet those parents may still claim to prefer that their children read print.

In our current households, children from a year-and-a-half are using tablets and engaging with content. When we ask the parents if that's cool with them, they say yes. "I use tablets when I need to keep my kids busy" or "I teach ABCs and 123s with tablets" or "If my child wants to read on a tablet, I'm okay with that...although I generally prefer for my child to read in print.

McLean cites some 10 percent of children's book purchases in the last quarter of 2014 in digital formats.

That compares to a 19-percent digital figure in terms of overall book purchases in Q4 2014.

'Show Off What They're Reading'

Teens' preference for print appears to be strengthening, in survey results McLean is tracking.

I think what's going on here is that the blush is off the rose in terms of understanding what books are for teens. They're settling into a habit of what they like in print. Partly they like to share them. Teens also like to carry books around, show off what they're reading. Partly because they're [print books] easier to get without a credit card, they like to use the library. And they also don't have the productivity needs [that many adults have] of carrying around lots of books on an e-reader.

McLean reiterated the dramatic statistic that Nielsen brought to the Digital Book World conference in January, McLean reminded us that some 80 percent of YA books in the US appear to be bought — and read by — adults.

And she showed a compelling comparison of bestseller charts from 2011 and from 2014, indicating that while only five of the top 20 juvenile titles in 2011 were YA books, the YA category dominated the juvenile category near the end of 2014, "almost to the exclusion of traditional juvenile books."

Graphics are from Kristen McLean's report to IDPF's Digital Book 2015: "Youth Reading - Or Not: What Do We Know?

Porter Anderson is the Bookseller's Associate Editor for The FutureBook, and with Jane Friedman produces The Hot Sheet industry newsletter for authors. He writes about publishing at Thought Catalog in New York and is a journalist, speaker and consultant; a Fellow with the National Critics Institute; a producer, news reader and reporter formerly with CNN International, CNN.com, The Village Voice, the Dallas Times Herald and other media. He programmes, produces and speaks at conferences regularly, most recently in New York, Los Angeles, London, Milan, Matera, Berlin, Frankfurt, Boston, Charleston, Singapore, St. Pete Beach, Stockholm and elsewhere. Porter Anderson's dream sponsor is Campari.